Feed mechanism for engine lathe



1970 KEMZQ WHAMA fi -fiffiwfifi'wfi FEED MECHANISM FOR ENGINE LATHE I Filed Dec. 5, 1966 3 Sheets-Sheet 1 19m KENZO AIHARA EAWiM FEED MECHANISM FOR ENGINE LATHE Filed Dec. 5, 1966 3 Sheets-$heet m I07 I06 r H05 Jan, 6, ETIU KENZO AHMARA FEED MECHANISM FOR ENGINELATHE 3 Sheets-Sheet 3 Filed Dec. 5. 1966 United States Patent 3,487,734 FEED MECll-lANlfill/i FGR ENGKNE LATHE Kenzo Aihara, Tokyo, Japan, assignor to llregai Tekko Kabushiki-Kaisha, Tokyo, Japan Filed Dec. 5, 1966, Ser. No. 599,000 lint. Cl. 1823b 21/00 US. Cl. 82--22 7 Claims ABSTRACT OF THE DISCLUSURE The normal cutting and serewdhread cutting operations can be selectively performed by a single lead screw and ball type nut mechanism. A stationary lead screw of the conventional construction has a ball type nut always meshing with the same and capable of being selectively coupled to and a changeover mechanism having at least three operative positions for the normal longitudinal and cross feeds and the screw-thread cutting feed. When in its operative position for the normal cutting operation, the changeover mechanism selectively allows either of rotations of the ball type nut and associated hand wheel to be transmitted to the ball type nut to move the apron. In the screw-thread cutting position the changeover mechanism causes the nut to be rotated at a rate higher than in the normal cutting operation. Accordingly the disclosed construction does not include a rack and a pinion previously used for the normal cutting operation as well as a half nut device and a mechanism for engaging and disengaging the device from the lead screw.

This invention relates to improvements in a feed mechanism for use in an engine lathe.

In order to effect longitudinal movement of a tool slide on an engine lathe, it has heretofore commonly been practiced to use two transmission systems. One of the transmission systems has been used to perform the normal cutting operation and includes a rotary feed shaft, a gear train disposed within an apron, and a pinion meshing a rack secured on the lathe bed, the apron being moved by the pinion rotated by the feed shaft through the gear train and the rack. The other transmission system has been used to perform the screw-threaded cutting operations and includes a rotary lead screw and a half nut engaging and driven by the lead screw to move the apron. These two transmission systems may be selectively operated by a changeover lever within a feed box switching the lathe from the normal cutting operation to any screw-thread cutting operation and vice versa, a lever within the apron operating the half nut and a feed disengaging lever.

Since the screw-thread cutting operations must be performed with a high accuracy of feed, the lead screw is exclusively used for that purpose. If the lead screw is used to effect feed in the normal cutting operation the same will become prematurely worn resulting in a decrease in accuracy of screw-thread cutting.

On the other hand, if it is tried to effect manual feed by the half nut through manual rotation of an apron handle, a great labor is required because that portion of a force transmitted from the half nut to the lead screw is unexpectedly low, being in the order of 30% of the torque provided by the lead screw. This is associated with the decrease in accuracy as above described to make manual rotation of the apron handle impracticable. For this reason a highly efficient combination of rack and pinion has been usually utilized.

Thus the conventional type of feed mechanism for use in engine lathes comprised necessarily two types of transmission systems as previously outlined and therefore had a complicated construction.

3,487,734 Patented Jan. 6, 1970 Further it is to be noted that if either one of the half nut and feed shaft is in operation the other must be in free state in order to avoid any damage thereto. Thus, upon changing one of both operations to the other, this leads to the necessity of manipulating the three levers or the changeover lever within the feed gear box, the feed disengaging lever within the apron and the lever for the half nut resulting in complexity of handling.

The primary object of the invention is, accordingly, to provide a new and improved feed mechanism for use in an engine lathe, simple in construction and easy in handling in which the abovementioned disadvantages are eliminated by the elimination of a rack and pinion mechanism previously used to effect longitudinal feed of a carriage, and by the provision of a ball type nut continuously meshing a lead screw, instead of a half nut mechanism also previously used in the screw-thread cutting operations, the ball type not being adapted to be rotated to effect longitudinal feed of the carriage suitable for either the normal cutting operation or any screwthread cutting operation as the case may be.

Another object of the invention is to provide a new and improved feed mechanism, for use in an engine lathe, and which imparts very little wear of the lead screw and the associated nut and is capable of retaining a high accuracy during long service.

A further object of the invention is to provide a new and improved feed mechanism for use in an engine lathe having an extremely high transmission efficiency with which a motive force is transmitted from a lead screw to the associated nut to permit manual longitudinal feed to be efiected with a low force.

According to a preferred embodiment of the invention there is provided a feed mechanism for use in an engine lathe, comprising, instead of the usual combination of a rack and a pinion serving to effect longitudinal feed of a carriage and of a half nut mechanism associated with a lead screw, a ball type nut continuously meshing with the stationary lead screw, said ball nut being selectively coupled to both a disengaging mechanism associated with a feed shaft (or a changeover mechanism having at least three operative positions or a first position where longitudinal feed for the normal cutting operation is effected, a second position where cross feed for the normal cutting operation is effected and a third position where a screw-thread cutting operation is effected) and a hand wheel.

Conveniently, the engaging and disengaging mechanism may be coupled to the feed shaft through a speed change mechanism.

These and other objects, features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a developed plan view in aligned section of an apron constructed in accordance with the principles of the invention, the section being taken substantially along the line IIII of FIG. 2;

FIG. 2 is a substantially front view of a carriage illustrating the positional relationship between a gear train, a feed shaft and a lead screw;

FIG. 3 is a substantially front view of the apron illustrated in FIG. 1 showing an arrangement of an operating lever and a handle wheel;

FIG. 4 is a sectional view of a speed change lever mechanism taken substantially along the line lV-IV of FIG. 1;

FIG. 5 is a perspective view of a cover member used with the speed change lever mechanism illustrated in FIG. 4;

FIG. 6 is a perspective view of a feed changeover mechanism;

FIG. 7 is a sectional view of an operation unit for the feed changeover mechanism of FIG. 6 taken substantially along the line VIIVII of FIG. 1;

FIG. 8 is a perspective view of the operating unit for the feed changeover mechanism illustrated in FIG. 7;

FIG. 9 is a substantially front view of the feed changeover mechanism illustrated in FIG. 6;

FIG. 10 is a fragmental perspective view of additional parts of the feed changeover mechanism; and

FIG. 11 is an enlarged sectional view of one portion of the apparatus illustrated in FIG. 1.

Referring now to the drawings and to FIG. 1 in particular, the reference numeral 1 generally designates an apron unit forming the essential part of a carriage, 2 and 3 housing portions made of casting for example, and 4 designates a front cover member for the housing portion 3. Disposed in the rear of the housing portion 2 and on the lefthand side as viewed in FIG. 1 is a protuberance 5 integrally formed therewith. The terms front and rear used in the specification are intended to be near to and remote from an operators position on the lower portion of FIG. 1. The protuberance 5 has carried therein a bevel gear 6 on its boss 7 supported through a pair of conical roller bearings 8 and 8' for rotation and also through a lock nut 9 against axial movement. The bevel gear 6 is arranged to be rotatable along with a driving shaft 10 longitudinally extending from a feed change gear box (not shown) and to be movable along the drive shaft together with the entire apron unit. To this end, the bevel gear 6 in the embodiment illustrated is operatively connected to the driving shaft 10 through a feather key 11 secured on the side of the bevel gear and inserted into a keyway 12 extending on the drive shaft 10.

The bevel gear 6 is continuously in engagement with another bevel gear 13 secured to the rear end of a spline shaft 14 extending in the transverse direction at the substantially same level as the driving shaft 10 (see FIG. 2) and rotatably mounted to the housing portions 2 and 3 through a pair of ball bearings 15 and 15'.

As shown in FIG. 1, the spline shaft 14 has a pair of composite gears 16-17 and 18-19 fitted thereunto for both rotational movement with and axially sliding movement along the shaft. Each composite gear serves to change the feed speed and includes a pair of gears 16 and 17 or 18 and 19 in unitary construction axially somewhat spaced away from each other to form a circumferential recess therebetween. The composite gears 16-17 and 18-19 are maintained in place by having the respective shifting yokes 20 and 21 fitted at one end into the circumferential recesses just described and secured on the other end portions to a pair of control bars 22 and 23. The control bars 22 and 23 are supported to the housing portions 2 and 3 for axial movement and have the front end portion projecting externally of the front apron cover member 4. The control bars 22 and 23 are also provided on the front end portions with grooves 24 and 25 for the purpose as will be apparent later.

In order to selectively move the control bars 22 and 23 in the axial direction, a single change lever 26 is provided on a cylindrical cover 27 disposed on the front apron cover member 4 (see FIG. 3). As clearly shown in FIG. 4, the change lever 26 has a spherical end 28 adapted selectively to engage the grooves 24 and 25 on the front end portions of the control bars 22 and 23 and an intermediate spherical portion 29 resting on a split seat 30-30 secured to the cylindrical cover 27. It will be seen that the spherical portion 29 and the split seat 30-30 forms a ball and socket joint. It will be noted that the composite gears 16-17 and 18-19, the speed change lever 26 and the associated components as above described are of the conventional design.

As shown in FIG. 2, a second spline shaft 31 is disposed in substantially parallel relationship directly above the first spline shaft 14. It is, however, to be noted that the spline shaft 31 is shown in FIG. 1 as being disposed to the right of the spline shaft 14 for the purpose of illustrating meshing of gears. The spline shaft 31 is rotatably mounted at both ends to the housing portions 2 and 3 through a pair of ball bearings 32 and 32'. The spline shaft 31 has fitted thereon a gear 33 capable of engaging and disengaging from the gear 16 of the composite gear 16-17, a gear 34, a gear 35 capable of engaging and disengaging from the other gear 17 of the composite gear 16-17, a gear 36 capable of engaging and disengaging from the gear 18 of the composite gear 18-19, and a gear 37 capable of engaging and disengaging from the other gear 19 of the composite gear 18-19 for rotation therewith in the named order from the rear end of the shaft. Further an intermediate gear 38 continuously meshing with the gear 34 and another intermediate gear 39 meshing with the gear 38 are rotatably mounted on a pair of cross shafts 40 and 41 through a pair of bearings 42 and 43 respectively. Each of the cross shafts 40 and 41 is carried at both ends by two opposed tumbler arms 44 and 44', and arms 44, 44 and a toothed sector wheel 45 secured to the arm 44' (FIGS. 1, 6 and 9) are mounted on the spline shaft 31 through a pair of bearings 46 and 46' respectively for rotation independent of rotational movement of the shaft 31.

In order to swing the pair of tumbler arms 44 and 44', the toothed sector Wheel 45 continuously meshes with a gear 47 having secured thereto a cross shaft 48 which, in turn, extends loosely through a hollow rod 49 (see FIGS. 1 and 6) and projecting beyond the apron front cover member 4. The hollow rod 49 is provided on that portion located within the cover member 4 with a radial projection 50 (see FIG. 1) and the cross shaft 48 has its free end portion on which a retaining ring 51 is secured as by The hollow rod or tubular sleeve 49 is provided on the free end portion of the wall with a pair of diametrically opposed longitudinal slots 52 (one of which is shown in FIG. 6) and the retaining ring 51 is also provided on the free end portion with a pair of diametrically opposed longitudinal slots 53 (see FIGS. 6 and 7) for the purpose of changing feed movements as will be described hereinafter. The free end portions of the hollow rod 49 and shaft 48, the retaining ring 51, an annulus 54 including a pair of diametrically opposed pins 55 adapted to selectively engage the slots 52 and 53 are accommodated within a cylindrical front cover 56 (see FIGS. 1, 3, 7 and 8) secured to the apron front cover member 4. The annulus 54 has secured thereto an operating or changeover lever 57 loosely projecting through a guide opening 58 in the form of a letter h written from right to left formed on the cylindrical cover 56 (see FIG. 8). The annulus 54 also has a radial protrusion 59 with a round end diametrically opposed to the operating lever 57 and adapted to be movable only along a circularly arc path within a guide slot 60 formed on the cylindrical cover 56 (FIG. 7).

On the other hand, as shown in FIGS. 6 and 9', the cross shaft 48 has secured at the inner end a ratchet arm 61 rotatable along with the gear 47 and having its free end formed into a V-shaped recess 62. Disposed on the housing 2-3 side is a click or detent 63 adapted to be urged into engagement with the V-shaped recess 62 at the free end of the positioning arm 61 by a compression spring disposed within a suitable stationary block 64. The ratchet arm 61 cooperates with the click 63 and the spring 65 to form click stopping means for selectively positioning the shaft 48.

A link 66 has one end pivoted at 67 on the projection 50 on the hollow rod 49 as shown in FIGS. 1, 6 and 9 and the other end pivoted at 68 on an arm 69 secured at an end of a cross shaft 70 as shown in FIGS. 1, 9 and 10. Thus it will be apparent that rotational movement of the hollow rod 49 in one or the other direction causes the shaft 70 to be rotated in the one or other direction through the link 66. The shaft 70 is disposed in parallel to the spline shafts 14 and 31 as previously described and carries an intermediate gear 71 through a bearing 72,

the intermediate gear 71 meshing with the gear 37 to drive a gearing as will be described hereinafter. The shaft 70 further has slidably fitted thereon a shifting yoke 73 for controlling a clutch as will be described later. The shifter yoke 73 is operatively coupled to the shaft 70 through a pin 74 fixed on the latter and extending through a cam slot 75 formed on the boss of the shifting yoke 73 as shown in FIG. 10. As also shown in FIG. 11, the shaft 70 is provided with a pair of circumferential grooves 76 and 77 disposed at a relatively short interval while the boss of the shifting yoke 73 is provided with a bore 78 extending radially of the axis of the shaft 70 having a ball 79 urged by a compression spring 80 inserted into the bore 79 to selectively engage one or the other of the pair of circumferential grooves 76 and 77 whereby click stopping or detent means is formed for maintaining the shaft 70 in a selected one of its two positions.

As shown in FIGS. 1, 2 and 9, a third spline shaft 81 is disposed in parallel relationship to the right of the second spline shaft 31 and at a level somewhat higher than the latter. The spline shaft 81 is rotatably supported to the housing portions 2 and as by a pair of ball bearings 82 and 82' and has the rear end portion projecting beyond the rear surface of the housing portion 2, which end portion has a bevel gear 83 secured thereon. The spline shaft 81 is further provided on the intermediate portion with a gear 84 adapted to engage and disengage from the intermediate gear 39 through swing of the pair of tumbler arms 44 and 44 thereby to connect and disconnect the shaft 81 to and from the spline shaft 31 respectively, and shaft 81 is provided also at the front end with a gear 85 continuously meshing with a gear 86 directly connected to a handle shaft 87 for a hand wheel 88 (also see FIG. 3). The spline shaft 81 also has mounted thereon a gear 89 through a bearing 90 for rotation independent of rotation of the shaft 81, the gear 89 meshing with the gear 71. Fitted upon the spline shaft 81 is a clutch portion 91 adapted to be rotated with the shaft and also to be displaceable axially by the-shifting yoke 73. The clutch portion 91 is provided with clutch teeth 92 capable of engaging and disengaging from the clutch teeth 93 on the gear 89.

As shown in FIG. 1, the housing portion 2 has a protuberance 94 extending integrally therewith in the rear and to the right thereof and higher in level than protuberance 5 as previously described. The protuberance 94 carries a ball type nut 95 through a radial bearing 96, a thrust bearing 97 and a lock nut 98 for rotation and without any axial play between the nut 95 and a lead screw 99 engaging the latter. It is to be noted that the lead screw 99 is maintained stationary. The ball type nut 95 includes a bevel gear 100 continuously meshing the bevel gear 83 as previously described. The lead screw 99 is provided with a ball passage 101 in the form of a helix communicating with a ball circulating passage 102 formed in the interior of the nut 95 with a multiplicity of small balls 103 movably disposed in both passages.

The construction thus far described has been disposed on the apron side and a construction on the side of a saddle from which the apron is pendent will now be described.

As shown in FIG. 2, a saddle designated at dot and dash line 104 has slidably carried thereon a cross slide 105 oper-atively coupled to a cross feed screw 106 which is, in turn, directly connected to a gear 107. The gear 107 is disposed on the saddle 104 at a position such that it is capable of engaging and disengaging from the gear 39 through swing of the tumbler arms 44 and 44'. The cross feed just described may be of the conventional design.

The arrangement thus far described is operated as follows:

The driving shaft transmits a driving power to the spline shaft 14 through the bevel gears 6 and 13. However if the control bars 22 and 23 are in their neutral position illustrated in FIG. 1 the composite gears 1617 and 18-19 rotatable with the spline shaft 14 mesh with no gear mounted on the spline shaft 31 as shown in FIG. 1. Therefore longitudnial and cross feeds are not effected.

On the other hand, the change lever 26 as shown in FIGS. 3 to 5 has, in addition to its neutral position, four positions I, II, III and IV (see FIG. 5) which the same can selectively occupy through its movement about the center of the intermediate spherical portion 29. If the change lever 26 is in its position I, the gear 16 meshes with the gear 33, while if the lever is in its position II the gear 19 meshes with the gear 37. With the lever 26 in its position III the gear 18 meshes with the gear 36, and with the lever in its position IV the gear 17 meshes with the gear 35. By considering the diameters of these gears as shown in FIG. 1 it will be readily apparent that as the change lever 26 is successively moved from its position I toward its position IV that the spline shaft 31 increases its speed of rotation.

When the change lever 26 is in the selected one of the positions I to IV, rotational movement of the spline shaft 31 causes the gears 34, 38 and 39 to be rotated due to their successive intermeshing with one another, and also causes the gears 37, 71 and 89 to be rotated (see FIGS. 1 and 2). However it is noted that rotational movement of the gear 89 in its position illustrated. in FIG. 1 is not yet transmitted to the spline shaft 81 because as yet gear 89 is notclutched into engagement by portion 91 fixed to said shaft 81.

If it is now desired to effect longitudinal feed, it is necessary only to move the operating lever 57 (see FIGS. 6 to 8) to its position A illustrated in FIG. 8. This causes the retaining ring 51 to be moved in the counterclockwise direction as view in FIG. 6 while pin 55 is maintained in engagement with the longitudinal lot 53 on the ring 51. This rotational movement of the retaining ring 51 causes rotation of the cross shaft 48 (see FIG. 1) and therefore of the gear 47 in the counterclockwise direction. As readily seen in FIG. 9, therefore, the sector wheel 45 meshing with the gear 47, and the pair of tumbler arms 44 and 44' are also rotated in the clockwise direction until the gear 39 mounted at the free ends of the tumbler arms 44 and 44 meshes with the gear 84. Thus rotational movement of the spline shaft 31 is transmitted through the gear 34, the gear 39, the gear 84, the spline shaft 81, the bevel gear 83, and the bevel gear to the ball type nut 95 whereupon the entire apron is moved along the lead screw 99 to effect longitudinal feed.

It is noted that the detent or click stopping mechanism designated by the reference numerals 61 to 65 in FIGS. 6 and 9 serves to maintain engagement of the gear 39 with the gear 84 by means of the action of the compression spring 64.

For cross feed, the operating lever 57 can be moved to its position B illustrated in FIG. 8. This causes the tumbler arms 44 and 44' to swing in the direction opposite to that in the abovementioned longitudinal feed to permit the gear 39 to disengage from the gear 84 and mesh with the gear 107 on the lower portion of the cross slide whereupon cross feed is effected.

For any screw-thread cutting operation, the operating lever 57 can be first moved from its position A for longitudinal feed or its position B for cross feed as the case may be to its screw-thread cutting position C or its neutral position in line N (see FIG. 8). Then the slot 53 on the retaining ring 51 align with the slot 52 on the hollow rod 49 and the tumbler arms 44 and 44' remain keeping the gear 39 in its neutral position where the latter engages neither of the gears 84 or 107. Under these circumstances, if the operating lever 57 is moved toward the apron about the center of the ball-shaped end 59 the pin 55 is moved from the slot 53 to the slot 52 on the rod 49. Then the operating lever 57 is thrown in the lefthand direction as viewed in FIG. 8 until it reaches its position C. This permits only the hollow rod 49 to rotate in the lefthand direction to pull the link 66. This pulling movement of the link 66 causes both the shaft 70 and the arm 69 secured thereto to be rotated in the counterclockwise direction as viewed in FIG. 9 as will be seen in FIG. 9 and the counterclockwise rotation of the shaft 70 causes the forward movement on the shaft of the shifting yoke 73 through movement of the pin 74 along the cam slot 75. As a result, the clutch teeth 92 mesh the clutch teeth 93. Thus rotational movement of the spline shaft 31 can now be transmitted from the gears 37 through the gear 71, the reduced diameter gear 89 which serves to increase the speed of rotation, and thence through the clutch 93-91, to spline shaft 81 and via the bevel gear 83 and the complemental bevel gear 100 to the ball type nut 95. Therefore the nut 95 is being rotated around the stationary lead screw 99 to move the apron at a speed higher than the speed of longitudinal feed whereby a desired screw-thread cutting operation can be performed.

The shifting yoke 73 is stable and maintained in either of its positions as previously described by means of a biased detent or click stopping mechanisms designated by the reference numerals 76 through 80 in FIG. 11.

From the foregoing it will be appreciated that the invention has provided a novel feed mechanism for an engine lathe utilizing a lead screw and a ball type nut always meshing with the screw. Therefore the invention eliminates the necessity of providing both the conventional rack and pinion arrangement for effecting longitudinal feed and the conventional half nut mechanism except for retaining the lead screw.

While the invention has been illustrated and described in conjunction with a preferred embodiment thereof it is to be understood that various changes in the details of construction and the combination and arrangement of parts without departing from the spirit and scope of the invention.

What I claim is:

1. A feed mechanism for use in an engine lathe having a lathe bed and a movable carriage and apron including a cross-slide and cross feed screw, comprising in combination:

(a) a feed drive shaft extending longitudinally of the lathe;

(b) a changeover mechanism having at least three selectively operative positions and including power transmitting means and a single operating lever means for and prescribed to effect alternatively the (1) longitudinal feed of said carriage for normal cutting operations,

(2) cross feed of said cross slide also for normal cutting operations, and

(3) screw-thread cutting operations, respectively;

(0) common means operatively connecting the changeover mechanism to said feed drive shaft;

(d) a single stationary lead screw fixedly connected to said lathe bed and disposed parallel to said feed drive shaft; said carriage being movable (longitudinally) relative to said drive shaft and stationary lead screw; and

(e) a rotatable ball type nut always engaging the lead screw and operatively connected with said feed drive shaft selectively through said changeover mechanism of paragraph (b) for selectively performing the aforesaid longitudinal feed and screw-thread cutting operations.

2. A feed mechanism as defined in claim 1 further including a hand wheel and rotary drive means associated therewith and with said nut for effecting manual movement of said carriage.

3. A feed mechanism as defined in claim 2, with said ball type nut being selectively coupled to the changeover mechanism through said power transmitting means, and also being directly coupled to the hand wheel and said rotary drive means.

4. A feed mechanism as defined in claim 1 wherein the means of paragraph (c) include a separate leveractuated shiftable rotary gear, speed changing mechanism disposed in said apron.

5. A feed mechanism as defined in claim 1 wherein the power transmitting means of the changeover mechanism of paragraph (0) include at least two different speed power trains of relatively interengageable rotary drive members; and said single operating lever means selectively shifts and connects one of said power trains with said drive shaft to effect the desired predetermined operative position.

6. A feed mechanism as defined in claim 5 further including selectively engagea-ble clutch means operative responsive to predetermined movement of said single lever operating means to connect the faster of said two different speed power trains into the power transmitting means.

7. A feed mechanism as defined in claim 1 and further including safety overload means whereby overloading of the lathe causes the drive train to be interrupted.

References Cited UNITED STATES PATENTS 557,031 3/1896 Schellenbach 8222 762,482 7/1904 Lodge et a1 82--22 3,023,631 3/1962 Curtis 8227 XR LEONIDAS VLACI-IOS, Primary Examiner U.S. Cl. X.R. 8227 

